912 resultados para YES, Aquatic toxicity
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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A novel, simple, rapid and eco-friendly method based on dispersive liquid-liquid microextraction using a bromosolvent was developed to determine six estrogenic mycotoxins (zearalenone, zearalanone, alpha-zearalanol, beta-zearalanol, alpha-zearalenol and beta-zearalenol) in water samples by liquid chromatography-electrospray ionization tandem mass spectrometry in the negative mode (LC-ESI-MS/MS). The optimal conditions for this method include the use of 100 mu L bromocyclohexane as an extraction solvent (using a non-dispersion solvent), 10 mL of aqueous sample (adjusted to pH 4), a vortex extraction time of 2 min, centrifugation for 10 min at 3500 rpm and no ionic strength adjustment. The calibration function was linear and was verified by applying the Mandel fitting test with a 95% confidence level. No matrix effect was observed. According to the relative standard deviations (RSDs), the precision was better than 13% for the repeatability and intermediate precision. The average recoveries of the spiked compounds ranged from 81 to 118%. The method limits of detection (LOD) and quantification (LOQ) considering a 125-fold pre-concentration step were 4-20 and 8-40 ng L-1, respectively. Next, the method was applied to the analysis of the environmental aqueous samples, demonstrating the presence of beta-zearalanol and zearalanone in the river water samples. (C) 2015 Elsevier B.V. All rights reserved.
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Fish bioassays are valuable tools that can be used to elucidate the toxicological potential of numerous substances that are present in the aquatic environment. In this study, we assessed the antagonistic action of selenium (Se) against the toxicity of mercury (Hg) in fish (Oreochromis niloticus). Six experimental groups with six fish each were defined as follows: (1) control, (2) mercury (HgCl2), (3) sodium selenite (Na2Se4O3), (4) sodium selenate (Na2Se6O4), (5) mercury + sodium selenite (HgCl2 + Na2Se4O3), and (6) mercury + sodium selenate (HgCl2 + Na2Se6O4). Hematological parameters [red blood cells (RBC), white blood cells (WBC), and erythroblasts (ERB)] in combination with cytogenotoxicity biomarkers [nuclear abnormalities (NAs) and micronuclei (MN)] were examined after three, seven, ten, and fourteen days. After 7 days of exposure, cytogenotoxic effects and increased erythroblasts caused by mercury, leukocytosis triggered by mercury + sodium selenite, leukopenia associated with sodium selenate, and anemia triggered by mercury + sodium selenate were observed. Positive correlations that were independent of time were observed between WBC and RBC, ERB and MN, and NA and MN. The results suggest that short-term exposure to chemical contaminants elicited changes in blood parameters and produced cytogenotoxic effects. Moreover, NAs are the primary manifestations of MN formation and should be included in a class characterized as NA only. Lastly, the staining techniques used can be applied to both hematological characterization and the measurement of cytogenotoxicity biomarkers.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Despite remarkable significance of Pantanal for the conservation of aquatic birds, the status of their populations, the spatiotemporal patterns of distribution and habitat use and structure of communities are little known. Thus, we studied three aquatic environments (Negro river, bays and salines) from 2007 to 2009 in the Nhecolandia Pantanal to verify the distribution and composition of aquatic birds and also if there is significant seasonal influence on these aspects. We adopted the transect method (288 hours of sampling) and recorded 135 species (7.834 individuals). The Negro river showed the highest diversity, while the salines the lowest. The similarity of aquatic bird communities was higher between bays and salines, followed by Negro river and bays and lower between salines and Negro river. The equidistribution is more variable in the salines and more stable in the Negro river. The environments strongly differ from each other in aquatic bird composition in space (habitat use and distribution) and time (seasonal water fluctuations). The diversity of bird community in the dry season varies significantly in the salines, followed by the bays and more stable in the Negro river. The Negro river, regardless of large annual amplitude of flow, is more seasonally stable since its riparian vegetation is continuous (not isolated) and constant. These aspects provide better conditions to stay all year, contributing to decrease the seasonal nomadic tendencies of aquatic birds. Finally, all these data provide strong arguments to the preservation of all phytophysiognomies in the Nhecolandia sub-region of Pantanal, but with special attention to the salines widely used by many flocks of aquatic birds (mainly in the dry season) and migrant and/or rare species restricted to this habitat.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This study aimed to evaluate feed preference and control efficacy of grass carp (Ctenopharyngodon idella) on the aquatic macrophytes Ceratophyllum demersum, Egeria densa and Egeria najas. An experiment was carried out at mesocosms conditions with 2,000 liters capacity and water residence time of 2.8 days. C. demersum, E. densa e E. najas biomasses were offered individually with sixty g and coupled in similar quantities of 30 g of each species, evaluated during 81 days, envolving 6 treatments. (1 - C. demersum, 2 - E. najas, 3 - E. densa, 4 - C. demersum + E. najas, 5 - C. demersum + E. densa and 6 - E. najas + E. densa). When offered individually, E. najas and C. demersum presented the same predation rate by grass carp, which was higher than E. densa predation rate. When plants were tested in pairs, the order of feed preference was C. demersum > E. najas > E. densa. E. najas and C. demersum percentage control ranged from 73 to 83%. No relation between biomass consumption and grass carp body weight gain was observed, probably due to differences in nutritional quality among macrophyte species according to fish necessities. Therefore, it is concluded that the use of grass carp is one excellent technique to control submersed macrophytes in Brazil.
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In the present investigation we studied the feeding habits of the fishes associated with aquatic macrophytes in the Rosana Reservoir, southeastern Brazil. Twenty fish species were collected during four field trips, regularly distributed across the dry and wet seasons. Focal snorkeling observations of the fishes were made over a total of six hours. Nine species were present in abundances of more than 1% and, therefore, had their feeding habits analyzed. Hemigrammus marginatus, Roeboides paranensis, Hyphessobrycon eques, Astyanax altiparanae, Serrasalmus spilopleura, and Bryconamericus stramineus were predominantly invertivores, with predominance of aquatic insects (Diptera, Ephemeroptera, and Trichoptera immatures) among their food items. The predominantly algivores were Apareiodon affinis, Serrapinnus notomelas, and Satanoperca pappaterra, with high frequency of filamentous blue-green algae, diatoms, clorophyts, and periderm. The different microhabitat exploitation plus diet composition suggests partitioning of resources and absence of food competition among the most representative fish species in the studied community, indicating the importance of the naturalistic approach to fish ecology studies.
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Uncaria tomentosa is a medicinal plant used in folk medicine by Amazon tribes. In this study the constituents of aqueous extract of U. tomentosa bark were quantified by chromatographic technique and its lethal concentration 50 (48 h) in Hyphessobrycon eques was determined. The chromatography showed high levels of oxindole alkaloids, quinovic acid glycosides, and low molecular weight polyphenols. The CL50 48 h was 1816 mg/L. Fish showed behavior changes at concentrations above 2000 mg/L, accompanied by a significant decrease of dissolved oxygen. At the highest concentration 100% mortality was observed attributed to oxygen reduction by the amount of oxindole alkaloids, polyphenols accumulation of the extract in the gills, and the interaction of these compounds with dopamine. In conclusion, the aqueous extract of U. tomentosa did not alter the chemical components and it was shown that U. tomentosa has low toxicity to H. eques; therefore, it can be used safely in this species.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)